1. Field of the Invention
The present invention relates generally to power plants, and more specifically to an energy storage tank for storing of energy in a deep water environment.
2. Description of the Related Art including information disclosed under 37 CFR 1.97 and 1.98
An electrical generating power plant for a city produces power in a turbine to provide electricity to various places. During a hot summer day, the demand for electrical power can be greater than the power plant is able to produce. During night, the demand for electrical power could be lower than the minimum electrical power that the plant is producing without shutting down. In the case of a nuclear power plant, the reactor cannot be shut down overnight.
Some prior art patents disclose inventions that attempt to address the above concern. U.S. Pat. No. 4,808,029 issued to Grupping on Feb. 28, 1989 entitled SYSTEM FOR SUBTERRANEAN STORAGE OF ENERGY discloses a system that uses abandoned salt caverns to store energy that is inputted from a power plant during low demand and withdrawals the stored energy when the demand is high. A liquid flows between two caverns that are at different elevations in order to produce a large pressure gradient between the caverns. The liquid is pumped into the highest cavern to store energy, and allowed to fall into the lower tank and through a turbine when energy is withdrawn. This type of energy storage requires two large reservoirs that are spaced at different heights. If a storage tank was to be used in place of the cavern, the tank would need to be strong enough to hold the high pressure liquid.
U.S. Pat. No. 4,092,828 issued to Garza on Jun. 6, 1978 entitled HYDROELECTRIC PLANT discloses a hydroelectric power plant operated by wave action and supported on an ocean floor. A cylindrical tank is used to form a reservoir for the sea water. The relatively high pressure water at the ocean floor is allowed to flow through a turbine and into an atmospheric pressure reservoir to drive a generator. Water is pumped out of the atmospheric reservoir by a pump driven by the up and down motion of the waves. This system is not an energy storage device that could be used to store extra electric power production during low demand, and then use the stored energy to produce electric power at high demand.
U.S. Pat. No. 3,677,008 issued to Koutz on Jul. 18, 1972 entitled ENERGY STORAGE SYSTEM AND METHOD discloses a system with a cavern below the surface connected to an above-ground lake by a water pipe, where the cavern has a ceiling that forms an air cavity. An air pipe connects the air cavity to a compressor and turbine power plant. High pressure developed in the cavern compresses the air in the cavity due to the height difference in the water levels between the lake and the cavern. The compressed air is driven through the turbine to generate electric power. The compressor supplies compressed air to the air cavity to displace water from the cavern to the lake for storage of energy. In this system, the motive fluid that drives the turbine is compressed air. Also, the system requires a large cavern to store the compressed air.